Flight One-a New Kind of Performance One Design Dinghy [Archive]

Doug Lord

08-10-2011, 04:51 PM

This is a concept that I hope to see spring to life in one or more designs-all with one thing in common: the very unique retractable single curved lifting foil/daggerboard( C-Foil ).* This was one of those ideas you get in the middle of the night that gets your heart pounding and your feet moving to find a notebook to write it down/sketch it out.
Flight One, Version 1:
--what it isn't: it is not a full flying hydrofoil like a Moth,
-
--what it is:
1) a performance single hander that can be sailed by two,
2) a performance single hander that is fun,easy, and exceptionally comfortable to sail,
3) a performance single hander that uses a retractable, single curved lifting foil( C-Foil) to increase speed and improve handling. The foil will support 60% or so of the total weight of the boat as boat speed increases.
4) a performance singlehander that uses a sliding seat with a backrest for added righting moment and exceptional comfort,
5) a performance singlehander with retractable foils to allow off the beach sailing. The single curved main foil( C-Foil) when retracted allows two replaceable tips to stick below the bottom of the boat so that the hull doesn't touch sand.
-
--history- the curved lifting foil( C-Foil) that is the centerpiece of this concept has a long history in the design of high performance sailboats. Starting many years ago in trimaran designs where they were developed to a high level in ORMA 60 footers and today in many multihull designs from the gigantic Banque Populaire to the Nacra 20, A Class and C class catamarans among many others. Relatively recently, dual curved lifting foils have been applied to the Open 60's with Virbac-Paprec 3 winning the Barcelona World Race by a large margin using them.
Well, that was one hell of an inspiration to me-the first time in history that lifting foils had been used on a keelboat to win a major ocean race. I thought a lot about it and it seemed like a natural to use these foils on dinghies-here is the original thread-including a bad idea I had that was to have the dual foils pointing outboard. Thanks to Greg Ketterman and others for straightening me out on that one:http://www.boatdesign.net/forums/sailboats/dinghy-design-open-60-influence-36401.html . But that all led to what seems like a good idea for a dual foil boat and then, after trying hard to come up with a simpler system, to my "eureka" moment with the single curved lifting foil( C-Foil ).
Reference material: http://www.boatdesign.net/forums/hydrodynamics-aerodynamics/advantages-disadvantages-curved-lifting-foils-monohulls-multihulls-37508.html
-- the idea: See the sketches below(and in subsequent posts as this concept is further refined). Basically, there is a single, curved asymetric foil( C-Foil ) that slides athwartship in a trunk that is partially open and jointed:
1) the top center of the trunk can be moved fore and aft to change the angle of incidence of the lifting portion of the foil only-the incidence of the vertical portion is not affected. The board can be accessed by hand or by other means to move if the auto system is not used.
2) the sliding seat mentioned above can be tied into the sliding board to allow automatic side to side board movement.
3) the relative side to side position of the board can be set with a simple "relativity" control that allows the total amount of vertical lift developed by the board on either side to be adjusted from max lift to almost no lift while still working automatically, if desired.
4) Since the board( C-Foil ) is not conceived of to lift the boat clear of the water(on a regular basis-stuff happens), there is no requirement for an altitude control system(wand) as on a Moth.
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--the rationale: Exceptional Comfort, Exceptional Ease of Sailing, Foil Assisted Speed and Performance!
=========
A note on the Flight One Concept: there are areas of this technology that could be patented but I am absolutely not interested in that. I'm interested in trying to inspire others to help refine this design or to use this technology with no strings to do their own design-with or without my help. I believe that this concept has incredible potential for developing a unique dinghy that could be a major breakthru in dinghy design. Much more to come!!
=============

* UPDATE- 8/11/11--To eliminate having to say "retractable single curved lifting foil/daggerboard", I'll just call it C-Foil from now on.

Rough Sketches-click on image:

Doug Lord

08-10-2011, 08:11 PM

Here are the specs on some singlehanded dinghies produced by RS in the UK:

1) RS 100(hiking)
LOA-14'
Beam 6'
hull shell 121lb
sailing weight 176lb
SA
asy spin 134 sq.ft.

=============

2) RS 300(hiking)
LOA-14'
Beam 6' 7"
hull shell 128lb
sailing weight 165lb
SA-rig A 99sq.ft.
rig B 107 sq.ft

==============

3) RS 600(trap)
LOA-14'8"
Beam 6' 4"-7'
hull shell 115lb
sailing weight 167lb
SA-main 131sq.ft.
reefed 114 sq.ft.

==============

4) RS 700(trap)
LOA-15' 5"
Beam 6' 4"- 7' 8"
hull shell 123lb
sailing weight 174lb
SA-main 137sq.ft.
spin 166sq.ft.

=====================

And some other modern singlehanders:

1) Contender(trap)
LOA-16'
Beam 4.92'
hull shell 180lb
sailing weight ???
SA-main 116sq.ft.

==============

2) Swift Solo(trap)
LOA-14.5
Beam 6.4'
hull 169lb
sailing weight-all up boat 196lb.
SA-main+jib 152sq.ft.
asy spin 265sq.ft.

===============

3) Musto Skiff(trap)
LOA-15'
Beam 7.7'
hull shell 121lb
sailing weight-all up boat-176lb
SA-127sq.ft.
asy spin 167sq.ft. sq.ft

================

Doug Lord

08-10-2011, 08:54 PM

Of all the singlehanded dinghies in the previous post not a single one uses "foil assist"-where a lifting foil of some type can reduce the displacement of the boat. In fact the only dinghies that do use foil assist are the I-14 and National 12, some Cherubs and the SK4 skiff as best I know now. Contrast that with a fairly large number of small beach cats and multihulls up to 20' that use lifting foils for "foil assist" as a matter of course.
Somethings not right here and it's going to change.
Foil assist on these monohulls lifts a small percentage of the overall sailing weight on these dinghies-for instance on the I-14, it is only 89lb nominally. On a Nacra 20 cat it can be a much higher percentage and lift is fully adjustable.
On Flight One the lift due to foil assist will be closer to a maximum of 60% and it will be 100% adjustable by the skipper. Note, that on these monohulls the vertical lift is from a rudder t-foil, which allows the crew to be further aft upwind or downwind adds to crew weight to hold the stern down. However, in very light wind these foils cause drag in excess of any improvement in speed. Thats where the curved ,retractable lifting foil( C-Foil ) comes in: in conditions where lift is not productive the lifting portion of the foil can be reduced without affecting the area required for lateral resistance!
If it is decided that a rudder T-foil will be beneficial, then Flight One will be able to use a system already devised for another boat of mine that allows a simple way to retract the rudder hydrofoil.
===============

--- UPDATE- 8/11/11--To eliminate having to say "retractable single curved lifting foil/daggerboard", I'll just call it C-Foil from now on.

===============
See pdf on rudder t-foils below:

pictures: L to R ,I-14 rudder t-foils, National 12 rudder t-foil.

Doug Lord

08-10-2011, 10:32 PM

DSS--One of the most recent developments in monohull "foil assist" is "DSS"-Dynamic Stability Systems invented by Hugh Welbourn. Here is a thread with his most recent-and coolest to-date-example of the system in action. Be sure to watch the exceptional video.
http://www.boatdesign.net/forums/sailboats/quant-28-foil-assist-keelboat-dss-38421.html

Haven't seen an example of DSS on a dinghy and I'm not sure whether it would work or not. It would be able to add RM and the crew would have to handle moving the foil every tack as with the single sliding curved foil on Flight One. But the boat would still require a foil for lateral resistance.
My gut feeling ,at this point, is that the curved lifting foil would be more efficient in developing vertical lift but the vertical lift from DSS would also add to the boats righting moment. I think it is too early to say that one system would definitely be faster than the other-both are "foil assist" and both have a lot of potential. DSS is actually being used on the remarkable Quant 28 and another sportboat "Brace,Brace, Brace". DSS is a tribute to Hugh Welbourn's ingenuity and persistence.
It does appear that the Flight one system( C-Foil ) would be significantly simpler and possibly have a greater range of adjustability and therefore be more suitable on a singlehanded dinghy.

========================
T-Foils (2)-Another configuration of "foil assist" for dinghies could be a version of the bi-foiler system pioneered by the Moth but with smaller foils and designed so as to not require an altitude control system(wand).
The main advantage of a system like this would be the absence of a sliding foil that has to be moved-by the sliding seat or directly by the crew.
The main disadvantages would be:
1) the lack of ability to reduce the area of the lifting foil to configure the system for different wind conditions. The Flight One system( C-Foil) is infinitely configurable to the lowest drag system for any condition.
2) According to Greg Ketterman the curved lifting foil will be significantly more efficient that the main t-foil in this kind of configuration.
3) One of the greatest advantages of a bi-foil configuration in a fully flying foiler is its ability to use veal heel. That would not be possible with the "foil assist" version of this configuration.
4) The main t-foil hydrofoil would not be fully retractable for beach sailing-it would always hit first unless some method was designed that allowed the foil to fit flush with the bottom.
-----
All in all, when compared to other forms of foil assist I'm convinced that the Flight One system( C-Foil) is simpler in every case and may be faster in most cases with a higher degree of vertical lift. It will definitely be more adjustable to varying conditions than any other system as best I can tell now.

Doug Lord

08-11-2011, 08:27 AM

Sliding Seat /Comfort--
This is as important to the Flight One concept( C-Foil ) as is the curved foil because the idea is to break the mold in performance dinghy design. That means getting away from super athletic torture chambers by using variations on movable ballast systems. The idea, to me, is to be able to sail a fast monohull in the most comfortable way possible to allow participation by people that might not want to hike or use a trapeze yet be able to, at least, match the performance of some trapeze dinghies. This is a tough bill to fill and will require quite a bit of development.
Sliding seats of one type are used by the International Canoe, the Skate and a maybe a couple of other boats. They are ,essentially, a plank that you sit on as far out as you can get. The variation I want to develop will be a bench seat with a backrest designed with major comfort in mind. The seat(one on each side) will be able to move quickly and create righting moment equivalent to a trapeze dinghy. I think a seat like this will encourage more people to give this kind of performance dinghy a shot because of the ease of use and comfort of the seat. In addition, the racks supporting the seat will be designed to have buoyancy pods far outboard that will prevent a capsize should the seat be in max position and the wind quit.
The seat will also be able to be used to move the foil side to side.....
===================
UPDATE- 8/11/11--To eliminate having to say "retractable single curved lifting foil/daggerboard", I'll just call it C-Foil from now on
===================

pic-Skate with twin sliding seats...click on image:

CutOnce

08-11-2011, 09:28 AM

All:

Trapezes are not torture - they are the most comfortable/economical/cost effective way of increasing righting moment - and this has been confirmed over many decades of voting (by real dollars spent) by a lot of sailors. Long before the Skates and other two man boats, the UK Hornet class used sliding seats.

Considering complexity, added weight, reliance on mechanical 2-D carriage & tracks (fore/aft as well as in/out), multiple bearing surfaces and use in a hostile corrosive environment, sliding seats do provide excellent righting moment augmentation - but with inherent compromises as well. This concept appears to be heading down the road to having two distinct seats - one for each side - adding more complexity yet again.

Traps add only two wires, tiny mast fittings and one harness to the equation - and they allow movement in three dimensions. A sliding seat adds a carriage and plank/seat - and it chews up a huge portion of precious real estate in an already small boat.

I know it is hard to resist the appeal of selling people on the idea of a dinghy slider-supported reclining Lazy Boy/Barcalounger.

In actual real world use, current sliding seats demand the same kind of athleticism, speed and reaction time as trapezes. Dancing around a sliding seat (in normal maneuvers) works in the single hand International Canoes, because you've got the very crowded and tiny dance floor to one's self. Putting all this (with individual port & starboard planks/seats) in the people space of a dinghy, along with dual trunk articulating adjustable curved lifting foil looks to be mildly challenging.

Please don't think of this as negative criticism - it is just to help outline some of the possible challenges in front of promotion of this concept. I very much look forward to full-sized demonstrations of this boat on the water - and hope it becomes a huge success. I'm sure innovative thinking will solve all these issues.

I also envy the ability to fund, promote, build and maintain all these projects concurrently.

Best Wishes!

--
CutOnce

Doug Lord

08-11-2011, 04:08 PM

Great comments, Once-thanks. I've always loved using a trapeze from when I was very young on a Flying Dutchman to more recently on a Hobie 16. I see no reason why a trapeze version using the single curved lifting foil ( C-Foil )technology
couldn't work very well.
My version of the concept will try to develop the sliding bench seat which I think may be less daunting to newer sailors than a trapeze and probably more comfortable to some people. The sliding seat on my version of the concept boat would also allow the seat to be tied into moving the foil side to side making that function pretty nearly automatic.
There is lots of room for different designs incorporating the C-foil and I hope others will take an interest in helping to develop designs suitable to utilize this technology to the fullest.

Doug Lord

08-12-2011, 09:45 PM

Some notes from the original thread where the C-Foil(single curved lifting foil) was first mentioned-edited for this thread:

A summary of thoughts on a single curved foil used on a dinghy for lateral resistance and vertical lift-so far-version 2:

1) First application I've found where a single curved foil could replace the two foils required in every other current application of curved daggerboards,
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2) Lots of potential, during the design process,to play with the radius of the curved board to maximize or minimize vertical lift,
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3) Seems that it may be superior to a "normal" daggerboard in every case including storage(retraction w/o hitting the boom, foil can be asymetric etc.),
-
4) Problems include how to grip the board to slide it from one side to the other.
Might be possible to use some sort of hand crank, line that rotates a drum between the two sides of the continuous trunk or? (See below)
-
5) Despite my first impressions earlier the C-Foil does not appear to be able to increase righting moment significantly, though this may change as the idea is refined. At the same time, the single curved foil does NOT decrease righting moment as does a curved lifting foil on a multihull.
-
6) When considering this single curved board system/ C-Foil it becomes abundantly clear that the use of curved lifting foils are not only possible on dinghies but can offer significant performance potential.
-
7) a boat using the single foil would be simple to right regardless of whether the boat capsizes to leeward or to windward using a righting line or maybe just crew weight hanging on the foil.(see rough illustration below)
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8) a major design advantage of the single curved foil/C-Foil-(with its continuous, partially open, athwartship curved trunk) compared to a t-foil used for "foil assist" is that in conditions where vertical lift produces too much drag the foil can be partially retracted eliminating the unwanted drag due to vertical lift. In addition, the foil can be retracted a small amount at a time to "tune" the vertical lift to the conditions. To further aid in this it appears that a system can be used that would adjust the angle of incidence of the vertical lifting portion of the foil(without affecting the lateral resistance portion) by designing the athwartship, partially open, continuous trunk for this facility.
-
9) A retractable gantry supporting a small t-foil rudder may or may not be an asset in pitch control for a dinghy using the single curved foil. A unique, rotating, rudder system where the rudder trunk actually rotates 180 degrees may be possible to allow the t-foil to be retracted 100% reducing unnecessary drag in light conditions. The rudder would still slide up and down within the trunk. It looks like a system like this could be done fairly simply and robustly-not much more complication than a kick up rudder design. More on this to come.
========================
Movement of C-Foil

I've looked at a lot of possible solutions for this including using some sort of roller that touched the board and allowed it to move with a hand crank or another means of causing rotation.
The breakthru comes in post #16 of this thread: http://www.boatdesign.net/forums/sailboats/quant-28-foil-assist-keelboat-dss-38421-2.html

Hugh Welbourn makes a comment-the first I've ever read- about how the DSS foil on the Quant 28 is moved. It has a roller in a wetbox where the shaft of the roller is sealed like a stuffing box-only simpler. Cranking or rotating the roller slides the foil athwartship! It is a brilliant idea for that boat and foil system and a version of it would work w/o the wetbox for the single curved dinghy foil. The break thru is the certain knowledge now that a roller system will work!
The foil is a single molded asymmetric foil that slides in a trunk across the boat.
When centered it is retracted and it can be deployed on the port or stb side and adjusted at will. Using the roller system it could be tied into a sliding seat so that it is automatically deployed tack to tack.

rough sketch L to R, 1) possible method of incorporating system similar in function to method of sliding DSS foil, 2) Method of righting C-foil equipped boat.

sharpii2

08-13-2011, 11:43 PM

An interesting idea.

The drawings do not indicate which way the boat is going, but I'll assume the convex side of the curve is to leeward and the crew is on the windward wing.

The only problems I see is there is a whole lot of foil area for the amount of lift being provided and it ends up not being well supported in the boat, when fully extended. Hoop like wings on airplanes were tried in the '30's and once in the '50's, but they never took off. And probably for the first reason I cited above.

Another problem is that the bending moments on this presumably high aspect ratio foil are going to be enormous. It's going to want to bend into a tighter circle. And when it does, it will produce more vertical lift which will make it bend even more. Being supported only at where it comes out of the hull, the load is going to be concentrated there. Where ever you have extreme localized bending stresses, there is bound to be trouble. Much of engineering is the art of avoiding situations like that. As the foil bends into a tighter circle, it is not going to want to retract back into its case. In order to keep it from binding, you are going to have to luff almost to a complete stop before you can retract it and shift it to the other side. This, in a very light boat with an enormous spread of sail, is going to be quite embarrassing. Especially when the boat fails to swing its bow over to start the next tack.

I can think of one possible design that would remove the need for the curved board but accomplish the same goal, lengthen the righting arm so more sail area can be carried.

What I have in mind would look like a cross bow from the top view.
A lengthy cross beam would have an angled foil at each end. Each angled foil would be supported at each end with a vertical board, which would serve as lee boards as the foil would not lift the hull out of the water, but merely move the center of buoyancy/lift to leeward. The crew, of course would move to the opposite end of the cross beam as human ballast. In this situation, there is no need for retraction of any kind. When the boat is level neither foil need go deeper than the hull. The foils would be angled inward, so when the boat heels, windward foil comes out of the water and the leeward foil produces more lift.

What you would have is essentially a trimaran with the floats removed and replaced with foils, with hopefully, a huge savings in whetted surface area.

The main hull would have a dead flat run on its bottom similar to a Brown Searunner trimaran. The main hull would plane, but only after it reached a relatively high speed. The main hull would be quite narrow. Maybe one eighth or even one tenth as wide as it is long.

Doug Lord

08-14-2011, 08:27 AM

Sharpii, thanks for the comments! I'm not really concerned about binding etc because these type foils are used regularly on beach cats and other multihulls under much, much higher loads. It's a question of engineering and building the foil properly which I think can be done fairly straight forwardly. The foil, as you surmised, operates on the lee side of the boat and, because of its unique design, can be an asymetric section. On the Nacra 20, the curved foils can be adjusted under load,and while they don't have as much curve as these do they are under much higher loads laterally. The foil develops both lateral resistance and vertical lift and if it and the trunk are properly designed adjustment should be straightforward-at least while tacking.
Boats I've sailed with either a CB or daggerboard were either impossible to adjust under load or very difficult. More will be learned with experimentation-the new test model I'm building and the fullsize boat it represents use curved foils like this one( same radius) that are under even heavier load so I'll learn a lot there.
>Just one other point: the C-Foil as used in the Flight One boat does not add anything to the righting arm/ righting moment and does not permit extra sail-carrying ability. In fact, if it is not sailed flat and allowed to heel to leeward it could actually reduce the righting arm!
--
Take a look at Doug Halseys 18' tri in the picture below-it seems to be similar to your idea and was designed and sailed without amas-just foils and seems to work well. Check out the rough sketches for the Tantra II; it uses dual curved foils(one at a time, generally) that do increase the RM of the boat. You can read more about it in the thread linked in the first post. See the picture of the original (35 years old)Tantra hull showing the molded-in leeboard concept that would house the curved foils on the updated version. And the C-foil for comparison.
Also, shown below the NACRA 20 foils, and the tight curved foils for the Farrier F31:
click on image:

Doug Lord

08-19-2011, 09:24 PM

I think a boat using the C-foil could represent very advanced technology in dinghy design since it allows much more vertical lift than currently used as foil assist. It offers the potential to be superior to any current dinghy that isn't a full flying foiler and the technology offers the design latitude to develop high performance dinghies that can be much easier to sail than current performance dinghies. It offers options such as the use of a rudder t-foil or not, extended tip foils that prevent the hull from touching ground. And more including greater range and adjustability than most any other foil system.
Design latitude is the key because this technology can be used in small single handers as well as two-three person performance designs. For the same RM the C-Foil allows much greater efficiency allowing the SA/ws ratio to be higher with significantly improved performance compared to older designs with the same RM.
It's exciting- take some time and check it out!

sharpii2

08-20-2011, 01:03 PM

Doug Lord

08-20-2011, 01:13 PM

Hi, Doug.

You got me thinking. And that is a very dangerous thing to do. I have strived years to develop a dangerous mind.

I started thinking about a boat similar in concept to the Quant but without a foil retracting mechanism. Then I thought of what to do when the foil nears the surface at speed. What if the bottom of it could become a planing surface, so it skips across the surface like a skipping stone.

That is how I came up with the contraption pictured below. The surfaces that are shaded are supposed to be below the waterline and the non-shaded ones are supposed to be above.

It is supposed to be sailed by a crew of two. Each wears a trapeze. One puts his feet on the edge of the wing deck and leans outward using the trapeze for support, while the other steers the boat.

As the boat heels, the foils on the leeward side produce more lift than those on the windward side and hopefully start lifting the boat. As the boat is lifted, its surface friction is reduced, allowing it to sail faster. As it sails faster, the leeward foils lift it even more, further reducing drag, and so on.

If it gets going fast enough, the main foil will break out of the surface of the water and start planing.

At least that's the thought.

I know the hull depth might not be enough, but this is to show the general concept.

As far as I know, the dagger board placement is correct.

Just thought I'd show you this for your entertainment.
====================
Thanks, Sharpii! According to the owner of the Quant 28 DSS works both when it is lifting in the "traditional" way and when it is just using the bottom surface,ie planing. I've always been concerned that the proximity of the lee foil to the surface might be a cause of too much drag but that is debunked by both Wellbourn and the owner to some extent. I'm sure more could be learned in two boat testing to see what happens with the foil planing and the other boat retracting their foil.
I think your idea is neat in its simplicity and might work well-you could fool around with foil areas and aspect ratio and do the boat fairly inexpensively.
I'll buy the beer if you get so interested you try it! Good thinking!

sharpii2

08-20-2011, 11:44 PM

====================
Thanks, Sharpii! According to the owner of the Quant 28 DSS works both when it is lifting in the "traditional" way and when it is just using the bottom surface,ie planing. I've always been concerned that the proximity of the lee foil to the surface might be a cause of too much drag but that is debunked by both Wellbourn and the owner to some extent. I'm sure more could be learned in two boat testing to see what happens with the foil planing and the other boat retracting their foil.
I think your idea is neat in its simplicity and might work well-you could fool around with foil areas and aspect ratio and do the boat fairly inexpensively.
I'll buy the beer if you get so interested you try it! Good thinking!

Thanks. Doug, for the kind words.

I was thinking of a name for this thing.

First I thought of 'mako', which is the fastest shark in the sea. Then I thought of 'tiger shark', then 'blue shark'.

The thing is, if it is ever built, I fear it could be beaten by a competently sailed windmill (which was where I got the beam and length from. The sail area is similar to a Hobie(r) 16, as far as I can remember it). So, to avoid severe future embarrassment, I chose to name it after what it most resembles: a surface to air missile.

Such naming of my designs is a tradition with me. Hence I have designs with names such as: 'box car', 'coal car', 'guppy', 'angel-fish' and even 'hog trough'.

Occasionally I will name a design in someone's honor, but only if I'm quite sure such a design will work as well as I hope.

If I ever get rich, I may well spend much of my fortune on mad boat experiments such as this. But, as a nine dollar an hour minus security guard, the only experiments I can afford to do are thought experiments.

Paper is cheap; it takes real money to innovate.

Doug Lord

08-27-2011, 11:19 AM

UPDATE: From the Quant 28 website-post 23, here: http://www.boatdesign.net/forums/sailboats/quant-28-foil-assist-keelboat-dss-38421-2.html
An illustration of the foil movement system that can be adapted to the C-foil
without the requirement for a sealed wet box. This can also be tied in to the sliding seat system(using a clutch) to allow fully automatic movement of the C-foil.

========================
Movement of C-Foil

I've looked at a lot of possible solutions for this including using some sort of roller that touched the board and allowed it to move with a hand crank or another means of causing rotation.
The breakthru comes in post #16 of this thread: http://www.boatdesign.net/forums/sailboats/quant-28-foil-assist-keelboat-dss-38421-2.html

Hugh Welbourn makes a comment-the first I've ever read- about how the DSS foil on the Quant 28 is moved. It has a roller in a wetbox where the shaft of the roller is sealed like a stuffing box-only simpler. Cranking or rotating the roller slides the foil athwartship! It is a brilliant idea for that boat and foil system and a version of it would work w/o the wetbox for the single curved dinghy foil. The break thru is the certain knowledge now that a roller system will work!
The foil is a single molded asymmetric foil that slides in a trunk across the boat.
When centered it is retracted and it can be deployed on the port or stb side and adjusted at will. Using the roller system it could be tied into a sliding seat so that it is automatically deployed tack to tack.

Doug Lord

09-04-2011, 12:45 PM

Basically, a boat using this concept will have a daggerboard replaced by a single "C-foil" of fairly high aspect ratio that not only generates the required lateral resistance but also generates vertical lift. The vertical lift can reduce wetted surface substantially helping planing to begin earlier and increasing top end speed. This is a more robust application of "foil assist"- already successfully proven on the International 14 and National 12 monohull dinghies as well as on Open 60 race boats like Virbec-Paprec 3 and Saffran and on numerous multihulls of all lengths and types. On an International 14 the vertical lift from the rudder foil is nominally around 95lb(of a 550lb sailing displacement-17%) whereas the C-foil can be designed to lift more than 50-60% of the boats sailing weight.
This concept is the first application of foil assist, that I am familiar with, that requires only a single retractable foil. The foil can be retracted 100% or be designed to be left partially below the hull . The foil can be moved side to side manually or be tied into to the movement of a sliding seat.
The foil can be "tuned" underway by partial retraction or by changing the angle of incidence without affecting the lateral resistance portion of the board.
I think that incorporating a foil like this with or without a small rudder "T-foil" can add a new performance dimension to single or doublehanded dinghy design.
=======================
The following is from Seahorse Editor Andrew Hurst. Seahorse is THE magazine of sailboat performance technology: (IMOCA 60= OPEN 60)

"A key reason for the positive camber boards on IMOCA 60's and some new VOR70's is that rather than providing maximum lateral lift when heeled, by being canted outboards(bottom out dl), instead gains are taken in generating vertical lift by leaning the asymetrical foils the other way(top outboard-dl).
Similarly, the curved foils used so successfully by Guillaume Verdier on his IMOCA 60 designs.
So (yet) another new world begins."

---
What is so cool about this is the recognition by the worlds premier sailing performance magazine of the importance of the developing vertical lift technology on monohull keelboats. And, as was proven and continues to be proven more and more frequently by the use of curved lifting foils on small multihulls(after having been pioneered and proven for years and years on large trimarans), the curved lifting foils on the Open 60's are perfect for numerous applications on smaller boats particularly dinghies where boats specifically designed to use this "foil assist" technology have the opportunity to carry the foiling revolution to another extraordinary step up in performance dinghy design.
=======
References: See http://www.boatdesign.net/forums/sailboats/dinghy-design-open-60-influence-36401-10.html post 137 is sort of an index---check it out.
=======

Pitures: L to R: 1) Single curved lifting foil(C-Foil) retracted in athwartship trunk for beaching, 2) C-Foil on stb tack-fully deployed, 3) V3-Verdier designed Open 60 and winner by a large margin of the Barcelona World Race-only the second Open 60 ever to use curved lifting foils, 3) V3's curved foils.

click on image-

Doug Lord

09-04-2011, 08:10 PM

Below is an updated version of the first post. The difference is that from now on* the Flight One / C-Foil concept will encompass a performance doublehanded dinghy design as well as a performance singlehander design also capable of being sailed fast with two people.These basic designs will be presented down the line along with more detailed information about the whole concept and any other designs using the C-Foil that may be conceptualized and/ or developed by others.
* thanks to Frank!
----

This is a concept that I hope to see spring to life in one or more designs-all with one thing in common: the very unique retractable single curved lifting foil/daggerboard( C-Foil ).* This was one of those ideas you get in the middle of the night that gets your heart pounding and your feet moving to find a notebook to write it down/sketch it out.
Flight One, Version 1:
--what it isn't: it is not a full flying hydrofoil like a Moth,
-
--what it is:
1) a performance doublehander or single hander that can be sailed by two,
2) a performance doublehander or single hander that is fun,easy, and exceptionally comfortable to sail,
3) a performance doublehander or single hander that uses a retractable, single curved lifting foil( C-Foil) to increase speed and improve handling. The foil will support 60% or so of the total weight of the boat as boat speed increases.
4) a performance doublehander or singlehander that uses a sliding seat with a backrest for added righting moment and exceptional comfort,
5) a performance doublehander or singlehander with retractable foils to allow off the beach sailing. The single curved main foil( C-Foil) when retracted allows two replaceable tips to stick below the bottom of the boat so that the hull doesn't touch sand.
-
--history- the curved lifting foil( C-Foil) that is the centerpiece of this concept has a long history in the design of high performance sailboats. Starting many years ago in trimaran designs where they were developed to a high level in ORMA 60 footers and today in many multihull designs from the gigantic Banque Populaire to the Nacra 20, A Class and C class catamarans among many others. Relatively recently, dual curved lifting foils have been applied to the Open 60's with Virbac-Paprec 3 winning the Barcelona World Race by a large margin using them.
Well, that was one hell of an inspiration to me-the first time in history that lifting foils had been used on a keelboat to win a major ocean race. I thought a lot about it and it seemed like a natural to use these foils on dinghies-here is the original thread-including a bad idea I had that was to have the dual foils pointing outboard. Thanks to Greg Ketterman and others for straightening me out on that one:http://www.boatdesign.net/forums/sailboats/dinghy-design-open-60-influence-36401.html . But that all led to what seems like a good idea for a dual foil boat and then, after trying hard to come up with a simpler system, to my "eureka" moment with the single curved lifting foil( C-Foil ).
Reference material: http://www.boatdesign.net/forums/hydrodynamics-aerodynamics/advantages-disadvantages-curved-lifting-foils-monohulls-multihulls-37508.html
-- the idea: See the sketches below(and in subsequent posts as this concept is further refined). Basically, there is a single, curved asymetric foil( C-Foil ) that slides athwartship in a trunk that is partially open and jointed:
1) the top center of the trunk can be moved fore and aft to change the angle of incidence of the lifting portion of the foil only-the incidence of the vertical portion is not affected. The board can be accessed by hand or by other means to move if the auto system is not used.
2) the sliding seat mentioned above can be tied into the sliding board to allow automatic side to side board movement.
3) the relative side to side position of the board can be set with a simple "relativity" control that allows the total amount of vertical lift developed by the board on either side to be adjusted from max lift to almost no lift while still working automatically, if desired.
4) Since the board( C-Foil ) is not conceived of to lift the boat clear of the water(on a regular basis-stuff happens), there is no requirement for an altitude control system(wand) as on a Moth.
-
--the rationale: Exceptional Comfort, Exceptional Ease of Sailing, Foil Assisted Speed and Performance!
=========
A note on the Flight One Concept: there are areas of this technology that could be patented but I am absolutely not interested in that. I'm interested in trying to inspire others to help refine this design or to use this technology with no strings to do their own design-with or without my help. I believe that this concept has incredible potential for developing a unique dinghy that could be a major breakthru in dinghy design. Much more to come!!
=============

* UPDATE- 8/11/11--To eliminate having to say "retractable single curved lifting foil/daggerboard", I'll just call it C-Foil from now on.

==================

Doug Lord

09-05-2011, 09:45 PM

As part of a continuing research effort on current dinghy design I will follow on from post #2 of this thread and highlight some interesting designs as this thread progresses in an effort to learn as much as possible about what other designer/developers are thinking......
------

Here is an interesting piece written by the designer of the Hartley Rebel skiff: http://www.rebelskiff.com/designers-notes/

An excerpt:

It’s not often that I get a commission to design a new high performance racing dinghy with such an unrestricted brief.

“We want a boat to be the show piece of our range; fast, challenging and at the leading edge of technology”

The recent movement from within the ISAF to investigate the possibility of a new high performance skiff for Women gave Hartley Laminates the perfect incentive to develop a truly fast and challenging boat suitable for Olympic standard women sailors.

In considering the overall parameters we determined the dominant factors were weight and overall size. We were determined to produce the lightest boat possible using state of the art, but economic, production techniques. Obviously weight is to a large extent dependent on size and we researched extensively to determine the minimum size which would support the ideal crew weight range of 120-140 Kg. in combination with other parameters such as overall righting moment, adequate rig size etc. This lead us to believe that a minimum waterline length of 4.4 meters was required if a smooth performance envelope across the wind range was to be achieved. In order to achieve this; the all up weight of the boat, hull, foils, rig, everything had to be no more than 90kg. This would amount to a considerable challenge in a mass production environment.

Length 4.5m / 14.8'
Beam Hull only 1.4m / 4.6'
Beam including racks 2.9m / 9.5'
Bare Hull weight 40kg / 88lb
All up sailing weight(not incl crew) including foils and sails 89kg / 196lb
Mast length 7.6m / 25'
Upwind SA- 196 sq.ft
--Jib area 5.7m2 / 61 sq.ft.
--Main area 12.5m2 / 135 sq.ft.
Downwind SA- 503 sq.ft.
--Gennaker area 28.5m2 / 307 sq.ft.
---------------------------------------------

NOTE: for reference material on many existing performance and daysailer dinghy designs try here: http://www.sailboatdata.com/firstpage.asp

---------------------------------------------

click on image:

Doug Lord

09-05-2011, 10:03 PM

Here is another new performance(borderline performance characteristics) singlehander by Keith Callaghan called the Hadron: http://www.bluelightning.co.uk/Hadron/Hadron01.shtm

Some info from Keith Callaghan:

Hadron is a new design for 2011. I have got back into racing dinghy design in the last few years, and in 2011 plan to get back into crewing Merlin Rockets - in particular MR3708 "Wicked". As part of my fitness training I am building a new singlehander design which I have developed from the same hull shape as "Wicked". Although the market is full of singlehander dinghies, the search is still on for a singlehander which will fulfill the requirements of the experienced dinghy sailer who is perhaps, like myself, getting on a bit, but who nonetheless demands high performance, and without too much pain. In other words, the boat must have impeccable handling characteristics, be comfortable to sit out and to sit in, easy to right after a capsize, and of course be fast and rewarding to sail. Just like a Merlin Rocket.

The rig is based around a standard carbon Merlin Rocket mast from Chipstow Boatyard.

Principal Dimensions:

Length over all 4.27 metres / 14'
Length on waterline 4.20 metres / 13.8'
Beam 1.95 metres / 6.4'
Hull weight 70kg / 154 lb.
Sail area 9.2 sq metres / 99sq.ft.
------------------------------------------
More designs from Mr. Callaghan: http://www.bluelightning.co.uk/

------------------------------------------
click on image:

Doug Lord

09-06-2011, 04:15 PM

Another Rebel from g-force dinghies( borderline performance characteristics) : http://www.g-forcedinghies.com/
one hull-two models:

•Produced in vinylester vacuum injection with a honeycomb core, a method previously only used in yacht building. The total hull weight is 78 kg.
•Due to this production method the hull is not just light but as well very strong and stiff. Stiffness is required to keep the boat handling easy while sailing at high speed or planing. The stiffness even remains after years and years of intense sailing!
•The hull has an extremely nice finishing comparing with PE or polyester boats.
•CE quality certificate and South African Boating Award 2006 winner in the category "non-powered trailerable craft".
•Standard equipped with a set of Pentex Mylar North Sails, mast and boom of Selden and Ronstan hardware.
The starting model "Fire" is equipped with jib and mainsail, and when the sailor is ready to go for true action the hull allows an easy adjustment of a gennaker pole and a total gennaker set to model "Radical" which can give the boat a speed of 20 knots at 15 knots true wind.

So not just a "new kid on the block" but a serious contender amongst the competition. Not just "another dinghy" but a very well over thought concept, developed by G-Force Yachts in close co-operation with International dinghy sailors.
Specifications-

"Fire" (no gennaker)
"Radical" (w gennaker)
Fire
Loa 4.323m / 14.18 ft.
Beam 1.48m / 4.85'
Weight(?) 78kg / 172lb
Upwind SA 8.65 sq.m. / 93 sq.ft.
Downwind SA 11.07 sq.m. / 119sq.ft.
--gennaker-2.42 sq.m. / 26 sq.ft.

Doug Lord

09-09-2011, 04:46 PM

For anyone interested in high performance-or just improved performance-in small boat design there is interesting information here: http://www.boatdesign.net/forums/multihulls/mayfly-class-catamaran-fischer-39616.html
Martin Fischer has done a very interesting design where he utilizes "shared lift" pioneered by Bill Roberts in multihulls-and among others Thomas Jundt in monohulls. He combines it in a unique way with curved lifting daggerboards and "J"- type rudder foils.
A boat like "Flight One" using a C-Foil could be designed in a similar way allowing the daggerboard to be further forward than on a "normal" dinghy increasing the distance between the lift of the daggerboard and the lift(up or down) of the rudder increasing pitch resistance. My concept has always been to increase the "foil assist" lift from the 17% on a I-14 upwind in 10 knots of wind to a figure between 50 and 70 % of all up weight in similar conditions for a design using the C-Foil.
Fischers cat in 10 knots of wind lifts 40% of the total weight.
So I think, for a monohull, the higher percentage of lift is an appropriate target along with the use of a variation of "shared lift".

Doug Lord

09-17-2011, 01:33 PM

Another interesting tidbit: in the multihull forum here is a story,by catsketcher(Phil Thomson) of his experience of sailing an ORMA tri-the boats that perfected curved lifting foils. He mentions that those foils can be adjusted under load which is pretty incredible. Also, the guys that sail the NACRA 20 say that their curved foils are pretty easily adjustable.
Just goes to show that a properly designed and engineered C-foil should be easy to handle in tacks and at other times that adjustment is necessary.

Doug Lord

09-24-2011, 08:33 PM

I've had some time to consider this concept some more and the most "serious"
negative I've been able to come up with is that the boat has to be wider at the waterline than is ideal in order to be able to fit the right size foil into the boat. That may or may not be a problem-I need to do some detailed design work before I'll understand that better.
The positives are pretty signifcant so far so we'll see.
What do you think, Mal?
------

Development Target: One of the most significant developments in foiler design may be a curved foil that uses a flap on the portion that lifts vertically(a basically straight section at the end of the foil,probably) that can be connected to a wand surface sensor rather than a Hobie trifoiler "feeler". The aspect ratio advantages of the curved foil(Greg Ketterman) would then be able to be easily adaptable to a retracting curved foil instead of using the "feeler" surface sensors on the non retractable, all moving Hobie Trifoiler foils. If anyone comes up with a good idea how to do it I will try it on the model in this thread: http://www.boatdesign.net/forums/multihulls/high-performance-self-righting-trimaran-test-model-36058-10.html
The results may be applicable to any boat using the right kind of curved foil.

sharpii2

09-24-2011, 11:56 PM

Doug Lord

09-25-2011, 08:11 AM

Hi, Doug.

Was just thinking of your concept.

It occurred to me that you will need two sets of pinch rollers to deploy the foil. One on the port side and one on the starboard. This is because so much of the foil will be deployed that little will be left in the boat. And what little is left will be on one side or the other.

You will also need a lock mechanism to keep the foil from being pushed back into the boat by its lift.

Come to think about locking mechanisms, I just thought of one to lock a swing keel down in more than one position. Had my boat had such a device, it might not have continued its capsize. There was a lock down position, but it was only with the keel all the way down. As the boat developed significant weather helm with the keel no where near vertical, my guess is that it was intended as a heave too device for survival conditions.

Back to Flight One. Have you considered a more conventional foil arrangement with the lifting foil being on the very bottom. The vertical portion could act as a dagger board, and since the lifting foil is not supposed to carry the entire weight of the boat, the vertical portion will stay immersed at act as a dagger board.

This would be much simpler than a foiler moth and the hull could be designed as a Hickman sea sled with a bit of keel, just a few inches, to project lower than the retracted lifting foil. Just a thought.
================
Thanks, Sharpii!-appreciate your thinking about this. Haven't given much thought to a locking system yet but I'll need some sort of system.
I've considered different foil systems but none with effective aspect ratio advantage of the curved foil as explained to me by Greg Ketterman and posted in the "Dinghy Design: Open 60 Influence " thread( http://www.boatdesign.net/forums/sailboats/dinghy-design-open-60-influence-36401-4.html post 54). The advantages of a curved foil, besides effective aspect ratio, include independent adjustment of the angle of incidence of the lifting portion or lateral resistance portion without interfereing with the other, ease of configuring for the conditions, and ease of retraction( or leaving two tips down as mentioned earlier).
If you get a chance, think about a system that allows a flap controlled by a wand surface sensor on a curved foil w/o interfereing with the other advantages of a curved foil-the "Development Target" in my last post. Right up your alley maybe-I'm having a mental block with it-at least, it's a pretty tough nut to crack.

Doug Lord

09-27-2011, 05:24 PM

I've had some time to consider this concept some more and the most "serious"
negative I've been able to come up with is that the boat has to be wider at the waterline than is ideal in order to be able to fit the right size foil into the boat. That may or may not be a problem-I need to do some detailed design work before I'll understand that better.
The positives are pretty signifcant so far so we'll see.
What do you think, Mal?
------

Development Target: One of the most significant developments in foiler design may be a curved foil that uses a flap on the portion that lifts vertically(basically a flat section at the end of the foil, probably) that can be connected to a wand surface sensor rather than a Hobie trifoiler "feeler". The aspect ratio advantages of the curved foil(Greg Ketterman) would then be able to be easily adaptable to a retracting curved foil instead of using the "feeler" surface sensors on the non retractable, all moving Hobie Trifoiler foils. If anyone comes up with a good idea how to do it I will try it on the model in this thread: http://www.boatdesign.net/forums/multihulls/high-performance-self-righting-trimaran-test-model-36058-10.html
The results may be applicable to any boat using the right kind of curved foil.
==================
I've found that there was a flap actuator for model airplanes that has a movement close to what I'm looking for. It was around 15 years ago or so and allowed a pushrod running spanwise in the wing to actuate a flap. Anybody remember this thing?
=================

Doug Lord

09-29-2011, 05:34 PM

CutOnce

09-29-2011, 06:53 PM

This is a potentially new foil and rudder system with applications probably limited to trimarans(at least for the main foils). But this may stimulate some thinking in the Great Quest to Eliminate the T-foil-at least in some areas. See post 145 here for more detail: http://www.boatdesign.net/forums/multihulls/high-performance-self-righting-trimaran-test-model-36058-10.html#post490418

I'm reminded of when I visited a friend's home during high school. His dad is a multiple doctorate pure math professor at Waterloo who worked at Los Alamos, Princeton and has published more papers than I could count. I saw a page or two of his work and picked it up to see if I could understand it. I stared and stared. His dad reached over and turned the paper 180 degrees and said, "Now it is upright". I still saw nothing recognizable.

--
CutOnce

Doug Lord

09-29-2011, 07:22 PM

I'm reminded of when I visited a friend's home during high school. His dad is a multiple doctorate pure math professor at Waterloo who worked at Los Alamos, Princeton and has published more papers than I could count. I saw a page or two of his work and picked it up to see if I could understand it. I stared and stared. His dad reached over and turned the paper 180 degrees and said, "Now it is upright". I still saw nothing recognizable.

--
CutOnce
==========================
Well, sorry about that-I thought I explained it fairly well in the other thread. I'd be glad to answer any questions you may have.

Doug Lord

10-01-2011, 09:01 PM

The major design aspect of the Flight one concept is the the single curved lifting foil used for "foil assist"-and not requiring any kind of altitude control. However, in versions of the boat where a lot of the boats weight is expected to be lifted by the main foil it will probably be advantageous to use a lifting foil on the rudder -perhaps with controllable angle of incidence.
In some boats that use rudder foil lift(up or down) for "foil assist" without any forward foil, "T"-foils have been used.
But it appears that a "J" foil would be significantly more efficient so the rudder system in the rough sketch below may be a good solution except for the fact, that as presently conceived, it would require two rudders-one retracted with every tack. I'm not entirely convinced that such a system, with its weight penalty, would be enough better than the "T"-foil to warrant its use on a foil assist monohull. There are monohull dinghies and scows that use dual rudders so I'm not ruling it out. More detailed research, which I am continuing, will allow a more informed comparative decision to be made-but it is an interesting possibility.
The system sketched previously(and again below) shows two rudders on one stock arranged so that one can pivot at a time. Each rudder would be sightly off the center line
and the whole stock could be pivoted to change the angle of incidence of the foil(both simultaneously). There would be one tiller and probably one extension tiller. It would not be as heavy as some dual rudder installations.
The simplest explanation of the advantage is that this type of rudder always has high and low pressure on only one side resulting in a better effective aspect ratio whereas a t-foil has high and low pressure on the same side(one side at a time) much of the time, most particularly upwind.
More on this here: post 54 http://www.boatdesign.net/forums/sailboats/dinghy-design-open-60-influence-36401-4.html See the link in the post.

Rough Sketch: Double "J" foil rudder- click on image- In this particular application the foil tip would always be pointed to windward with the rudders swapped out between tacks. The main advantage is upwind-as I understand it now.

Doug Lord

10-22-2011, 02:17 PM

Had a bit of a surprise today with a visit by Hugh Welbourn-DSS technology inventor and designer of very fast sailboats. See here for more on the story and pictures: http://www.boatdesign.net/forums/multihulls/high-performance-self-righting-trimaran-test-model-36058-11.html post 154
I discussed the Single Curved Lifting Foil with him and he was impressed saying that it was very workable-and a really neat idea. From one of the modern pioneers in the application of lifting foils to monohulls that meant a lot to me.

Here are the rough sketches of the foil, again:
The foil slides in an athwartship partial trunk and replaces a t-foil for foil assist.
click on image-

Doug Lord

11-05-2011, 07:13 PM

I was working on a curved foil for the SRT project and decided to see how the single curved foil would actually work on a real boat.
Boat is 16', 459 lb all-up. The underwater portion of the curved foil was 4' long. The portion of the foil doing the lifting was 1.3sq.'. The aspect ratio of the underwater portion was 7/1. The chord was .57'. The idea was to see what it would take to lift 50% of the all up weight.
The results were:
6mph/ 5.2 k speed,lift= 91lb which was 20% of the all up weight,
8mph/ 7 k speed, lift= 161lb= 35% of all-up weight,
10mph/ 8.7 k speed,lift= 195lb=42% of all-up weight,
12mph/ 10.4 k speed,lift= 241.6lb= 53% of all-up weight,
15mph/ 13k speed, lift= 377.5=81% of all-up weight.
----
The foil would be adjustable allowing the angle of incidence to be varied, the area to be varied and the foil to be 100% retracted. As a "foil assist" board
it looks like it should work well.

Doug Lord

04-18-2012, 08:02 PM

After thinking about this for a long time I'm thinking that a dinghy application of a curved lifting foil might be considerably improved by using two foils at least in some applications as I mentioned once before.
Using two foils would allow a narrower hull with greater overall beam and would allow the curved foils(or "L") foils to add righting moment in addition to vertical lift.
An "L" foil would be mostly retractable and out of the water when the boat is heeled slightly. The "Flight One" concept, using a single curved lifting foil, still is one of the simplest possible incarnations of "foil assist" for a dinghy.
rough sketches:

awhapshott

04-21-2012, 03:59 PM

Doug Lord

04-21-2012, 04:14 PM

An interesting design. Most Cherubs are now on the T-foil, and it is very handy; Not only is the upwind speed good, but the stability increase is well worth having, even if it does make things a little boring (I haven't got the daggerboard out the water on a T-foil boat yet)
The SK4 foil is brilliant, its planing ability and speed are amazing, although after collision with some Southampton mud at >20kts she is having some serious repair work done.

With the C-foil, how would the angle of attack be changed? Or would it be fixed?

Also, in one of your posts there was a thin red hull, with boards/floats projecting under the wing, what on earth is it? It looks like an early moth development.
=======================
I must have missed something-what is the SK4?? Found this: http://www.sailingsource.com/cherub/forum/index.php?topic=51.5;wap2
The single curved lifting foil would be adjusted just like any curved foil is: the foil would be angled fore and aft and the trunk on each side would be designed to allow that. It could also be done with a slight pivot of the athwartship trunk-though the more I've considered it the less I think a side to side trunk is required.
----
The boat in my last post is based on the Tantra which, I think, is the one you're referring to. It was a prototype using asymetrical, toed-in "leeboards"
for lateral resistance. Each leeboard had a replaceable tip. Wish I had thought using twin curved foils back then!

Pictures: Tantra, with 80 sq. US1 rig, circular cockpit with forward traveler, experimental square top rig designed 1975, built 1977. The Tantra II in my last post would be very similar---